System and method for imaging and treatment of tumorous tissue in breasts using computed tomography and radiotherapy

ABSTRACT

The present invention provides a system  10  for irradiating a breast  20  of a patient  22 . The system  10  comprises a gantry  12  rotatable about a horizontal axis  14  and comprising a radiation source  16  for generating a radiation beam  18  and a detector  24  spaced from the radiation source  16 , and a barrier  26  disposed between the patient  22  and the gantry  12 . The barrier  26  is provided with an opening  30  adapted to allow a breast  20  passing therethrough to be exposed to the radiation beam  18 . In some embodiments, the barrier  26  is provided with an opening  30  adapted to allow both the breast  20  and the tissue leading from the breast to axilla and the muscle tissue of the adjacent chest wall passing therethrough to be exposed to the radiation beam  18.

FIELD OF THE INVENTION

This invention relates generally to a system and method of providingradiation imaging and/or treatment and in particular, to a system andmethod for imaging and treatment of tumorous tissue in breasts usingcomputed tomography (CT) and radiotherapy.

BACKGROUND

Radiological evaluation of breasts is important not only for earlydetection of disease in breasts, but also for staging, treatmenttargeting and monitoring responses to treatment. Conventional x-raymammography has been shown a cost-effective tool for early detection ofbreast cancer. In conventional x-ray mammography, a breast is positionedon a platform and compressed with plastic plates. The breast iscompressed in order to even out the breast thickness so that the correctdose of X-rays can be delivered for clear images without over exposurein thinner regions and under exposure in thicker regions and also tospread out the tissue to reduce the likelihood of obscuring benign andmalignant lesions at different tissue levels. Two images of the breast,medio-lateral oblique (MLO) and cranio-caudal (CC), are typically madeat an oblique angle to each other to increase the likelihood of seeingfeatures in the breast that are not recognizable from one direction, butwhich may be discernable in another direction.

The predictive value and specificity of x-ray mammography remain limitedhowever, due to projecting a three-dimensional object into atwo-dimensional image and due to poor contrast detectability.Incorrectly diagnosing malignant tissue as healthy can result in missingcancers in their early stages while incorrectly diagnosing healthytissue as malignant can lead to unnecessary surgical procedures. Inindeterminate cases, biopsy is often necessary, despite thedisadvantages of high cost and the stress imposed on patients.

Cone beam CT systems have been used to provide three-dimensional imagesof uncompressed breasts of patients. In cone beam CT, a patient lies ina prone position on a couch having a hole in it. The patient's breastextends down through this hole and a cone beam CT machine rotates aroundit about a vertical axis of rotation. This system has minimal radiationdose to the rest of the patient's body (including the heart and lungs)since only the breast itself is exposed to the radiation beam. Onelimitation of this type of system is that it only images the breastitself without providing image information on the important soft tissuebetween the breast and the axilla (arm pit) where primary breast lesionsoften spread to infect lymph nodes in this region. Another limitation isthat it cannot make immediate use of widely available CT gantry systemsand external beam radiotherapy systems, which primarily have axes ofrotation that are horizontal.

Spiral CT scanners have been used to produce images of breasts andsurrounding tissues. In spiral CT, a patient lies on a couch, which ismoved into a gantry where a radiation source rotates many revolutionsabout a horizontal axis of rotation to produce the spiral. Since theradiation source is always pointed directly at the patient as it movesaround, all the tissue of the chest adjacent to the breasts is exposedto the radiation beam from multiple directions to produce continuousflow of images in relative short period of time. One limitation of thistype of system is that it scans not only the target breast andsurrounding soft tissue, but also simultaneously exposes the heart,lungs and other body parts to unnecessary radiation.

Accordingly, there is a need for an improved system and method forcomputed tomography of breasts and radiotherapy of tumorous tissues inbreasts.

SUMMARY OF THE INVENTION

The present invention provides a system and a method useful in cone beamcomputed tomography and radiotherapy. In some embodiments, the presentinvention provides a structure for use in irradiating a portion of abody in a gantry. The structure is adapted to be positioned between thebody and at least a portion of a radiation beam and provided with anopening adapted to allow a portion of the body passing therethrough tobe exposed to the radiation beam. The structure can perform one or morefunctions of a radiation barrier, a physical barrier, a support, apositioning device and an immobilization device for use in irradiating,for example, a breast of a patient in a gantry. In some embodiments, thestructure is in the form of a barrier. In the present specification,numerous embodiments are illustrated with a structure referred to as abarrier, which may function, for example, as a barrier to radiation or abarrier between a patient area and moving parts of the equipment. Itwill be appreciated that in each of these embodiments, if desired thestructure may or may not comprise a barrier and may or may not performdifferent or additional functions. The barrier can be positioned betweenthe patient and the gantry so that the patient can rest against it andis supported. In some embodiments, the barrier comprises a material thatabsorbs the non-breast-irradiating part of the radiation beam to protectthe healthy parts of the body from unnecessary irradiation. In someembodiments, the barrier functions to physically prevent collisionbetween any parts of the patient's anatomy with moving parts of thegantry. The barrier is provided with an opening adapted to allow abreast passing therethrough to be exposed to the radiation beam. In someembodiments, the barrier is provided with an opening adapted to allowboth the breast and the axillary extension of the breast to be exposedto the radiation beam. As used herein, an axillary extension of a breastrefers to any soft tissues leading from the breast to the axilla orarmpit. In several embodiments, an opening for e.g. a breast and anopening for e.g. an arm are described. It will be appreciated that asused herein, such description may comprise a single opening adapted toallow both to pass through. Thus, for example, a first opening and asecond opening as used herein may refer to a single opening as well asto a plurality of openings.

In some embodiments, a holder can be attached to the barrier forsupporting the breast. The holder can be a hollow cylinder and comprisean end cap that is removable to facilitate positioning of the breast inthe holder. The hollow cylinder can be provided with a vacuum line forevacuating the holder so that the breast can be more completely drawninto and stabilized in the hollow cylinder. A soft gasket can beprovided to vacuum seal the breast in the cylinder.

In some embodiments, the barrier is provided with a plurality of holessurrounding the opening area for preventing formation of vacuum in aregion beyond the breast.

In some embodiments, the holder is an open ledge that supports thebreast from below with no vacuum environment. This support ledge can bea simple flat surface oriented horizontally or at some small angle (e.g.5 to 30 degrees) to the horizontal. In some embodiments, this open ledgehas the curved shape of a half cup. In some embodiments, this ledge is acombination of flat and curved surfaces. In some embodiments the breastsupport is a flexible material that provides positioning andimmobilization much like that of a brassiere.

The barrier can be in the shape of a cone, partial spheroid, manyfaceted pyramid or any arbitrary combination of flat and/or curvedsurfaces that support and/or protect the patient while allowing properX-ray exposure of the breast and its axillary extension from the movinggantry. In some embodiments, the barrier can comprise an inner sectionand an outer section. The inner section is detachable from the outersection and provided with the opening adapted to allow a patient'sbreast and arm passing therethrough. In some embodiments, the innersection is rotatable with respect to the outer section such that thelocation of the opening in the barrier is changeable.

In another aspect, the present invention provides a method ofirradiating a patient's breast. In an embodiment, a barrier is providedbetween a patient and a gantry. The gantry includes a radiation sourcefor generating a radiation beam and a detector spaced from the radiationsource. The patient is positioned in a substantially upright position.The patient's breast is then extended through an opening in the barrierto be exposed to the radiation beam. The gantry rotates about ahorizontal axis, whereby the breast is irradiated by the radiation beamand detected by the detector.

In some embodiments, the method further comprises the step of extendingthe tissue leading from the breast to axilla through an opening in thebarrier. In some embodiments, the method further comprises the step ofextending an arm of the patient through an opening in the barrier.

In some embodiments, the radiation barrier can be provided with threeopenings adapted to allow either the left or right arm of a patientpassing therethrough either of two of the three openings, as either theleft or right breast, respectively, passes through the third opening, sothat either breast can be irradiated sequentially without modificationof the barrier.

In a further aspect, the present invention provides a system forirradiating a patient's breast. The system comprises a gantry whichcomprises a radiation source for generating a radiation beam and adetector spaced from the radiation source, and a barrier disposedbetween the patient and the gantry. The barrier can comprise a materialthat absorbs the part of the radiation beam that is not incident on thebreast and related tissue and is provided with an opening adapted toallow a breast passing therethrough to be exposed to the radiation beam.In some embodiments, the barrier is provided with an opening adapted toallow both the breast and the tissue leading from the breast to axillapassing therethrough to be exposed to the radiation beam. In someembodiments, the barrier comprises an opening adapted to allow an arm ofthe patient passing therethrough.

The system can comprise a holder for supporting the breast. The holdercan be substantially cylindrical and comprise an end cap that isremovable to facilitate positioning of the breast in the holder. Theholder can comprise a gasket for vacuum sealing the breast in theholder. The holder can also be provided with means for providing vacuumto facilitate positioning and stabilizing of the breast in the holder.The system can further comprise a panic button coupled to the vacuummeans, which when pushed, turns off the vacuum in the holder.

In some embodiments, the system can comprise a radiation sourcegenerating a cone x-ray beam in a keV energy level suitable fordiagnostic imaging. In some embodiments, the system can comprise aradiation source generating a cone x-ray beam in a MeV energy levelsuitable for therapeutic irradiation. The system can further comprise acollimator for producing a radiation beam having a sharp vertical edgeand semi-circular cross-section.

In some embodiments, the gantry can comprise a first radiation sourcefor generating a first radiation beam suitable for diagnostic imagingand a second radiation source for generating a second radiation beamsuitable for therapeutic imaging and/or treatment. The first and secondradiation sources can be attached to a common gantry. Alternatively, thefirst radiation source is attached to a first gantry, the secondradiation source is attached to a second gantry, and the first andsecond gantries are rotatable about a common axis.

In some embodiments, the patient lies prone onto a barrier layer that issubstantially horizontal in orientation, the breast hangs down through ahole in the barrier, and the gantry rotates about a vertical axis. Aslot is provided in the barrier and a cylinder is attached to thebarrier in such a way that the arm nearest the breast extends down byand past the breast in a way that allows clear X-ray exposure of thebreast and its axillary extension and the chest wall without exposingthe heart and lungs and so that no collision occur between body partsand the rotating gantry. Special rotation sequences and trajectories maybe used to minimize the X-ray dose exposure to the arm and shouldertissues and bones, from this arm insertion.

In some embodiments, the patient's head-to-foot orientation can be inany plane from vertical to horizontal, or stated alternatively, theangle between patient's head-to-foot orientation and a vertical axis canbe at any desired angle.

In one embodiment, the system may include a couch top moveable relativeto the gantry and a support attachment coupled to the couch top. Thepatient may lie down on her side on the support attachment duringimaging. The support attachment may comprise a drop-down or raise-upportion adapted to patient's built. In an embodiment, the attachment ismoveable in three directions (x, y, and z). In another embodiment, theattachment is moveable independent of the couch top. In a furtherembodiment, the attachment may include a central portion and two wingportions, each of which being adapted to support the patient in a lyingposition. In some embodiments, each of the two wing portions isattachable and/or foldable.

For radiation therapy treatment, one embodiment has both a kilovoltagex-ray source and flat plate detector and a megavoltage x-ray source anddetector, mounted at 90 degrees to each other on a single rotatinggantry. In one particular embodiment, the kilovoltage source is placednear the outside boundary edge of the gantry volume in the direction ofthe patient. The latter permits the minimum bending of patient anatomy,such as the neck, to allow imaging of important areas, such as themuscle wall of the chest, with minimal exposure of sensitive healthyregions, like the head and neck. The megavoltage x-ray source can belocated in a more central part of the gantry volume that is notconducive to the same boundary edge beam locations as a kilovoltagesource. The gantry can also be positioned to several (e.g., 2 to 8)specific angles and orientations, to deliver a prescribed megavoltagedose to the breast, or to a restricted volume in the breast, without alarge dose being delivered to other sensitive areas, such as the head,neck, heart and lungs. With the embodiment discussed here, the location,extent, shape, orientation and/or boundaries of the malignant tumor areprecisely determined in 3 dimensional space, relative to the gantrysystem coordinates, by the kilovoltage source and detector's acquisitionof a cone beam CT data set. These data are analyzed to either comparethese specifications to a preexisting treatment plan or to produce a newor a modified treatment plan. Then the desired dose, to the whole breastand/or to its axillary extension and/or to its adjacent chest wallmuscle, or to a restricted volume containing the malignant tumor, isthen accurately delivered by the megavoltage source, monitored by theflat panel megavoltage sensor, all on the single gantry and all duringshort time span (less than 30 minutes) for a single dose delivery. Sincemegavoltage x-ray beam radiotherapy is routinely administered in manyseparate daily doses, called fractions, over many weeks, this embodimentallows some determination of the tumor's response to treatment. Thisresponse can be indicated by comparisons to earlier fractions, asevident by changes in location, extent, shape, orientation, boundaries,or by detection of contrast agents related to functional, biologicaland/or structural characteristics, where these agents are administeredas part of the treatment setup and delivery, and as evaluated by conebeam CT data set viewing and analysis procedures. These 3 dimensionaldata sets can be extended to the 4^(th) dimension time by usingrespiratory gating during cone beam CT acquisition to correlate positionwith the phase of the patients breathing process.

For some embodiments, the barrier is adapted to incorporate a ring ledgethat allows the patient to be positioned further inside the rotatinggantry so that the shaped x-ray beam and/or beams strike the breast,and/or its axillary extension and/or its chest wall section of thepatient, without the need to move the x-ray source and/or sources, tothe outside perimeter of the housings, but remain in the central regionof the source enclosure, as is characteristic of most standard rotatingC-arm x-ray sources and imager panels.

BRIEF DESCRIPTION OF THE DRAWINGS

These and various other features and advantages of the present inventionwill become better understood upon reading of the following detaileddescription in conjunction with the accompanying drawings and theappended claims provided below, where:

FIG. 1 schematically illustrates a radiation system including a barrierbetween a patient and a gantry in accordance with an embodiment of thepresent invention;

FIG. 2 schematically illustrates an uncompressed breast extended throughan opening in a barrier and supported in a holder in accordance with anembodiment of the present invention;

FIG. 3 is a plane view of a barrier having openings therein inaccordance with an embodiment of the present invention;

FIG. 4 is a plane view of a barrier having openings therein inaccordance with an embodiment of the present invention;

FIG. 5 schematically illustrates two radiation beams generated from tworadiation sources arranged at 90 degrees in accordance with anembodiment of the present invention;

FIG. 6 schematically illustrates a radiation source and a collimator forproducing a radiation beam in accordance with an embodiment of thepresent invention;

FIG. 7 is a cross-sectional view of a radiation beam produced by theradiation source and collimator illustrated in FIG. 6;

FIG. 8 schematically illustrates a radiation system including a barriernear a patient in accordance with another embodiment of the presentinvention;

FIG. 9 schematically illustrates an uncompressed breast extended throughan opening in a barrier and supported in a holder having a surfaceconformal to a portion of the breast in accordance with anotherembodiment of the present invention;

FIG. 10 is a side view illustrating a radiation system including anadjustable barrier in accordance with an embodiment of the presentinvention;

FIG. 11 is a front view illustrating a radiation system including anadjustable barrier in accordance with an embodiment of the presentinvention;

FIG. 12 schematically illustrates a radiation system including a barriercoupled to a moveable couch top in accordance with an embodiment of thepresent invention;

FIG. 13 schematically illustrates a radiation system including a barriercoupled to a moveable couch top in accordance with another embodiment ofthe present invention;

FIG. 14 schematically illustrates simultaneous irradiation of bothbreasts of a patient in accordance with an embodiment of the presentinvention;

FIG. 15 is a side view illustrating a moveable support attachmentsupporting a patient in a lying position in accordance with anembodiment of the present invention;

FIG. 16 is a top view illustrating a moveable support attachmentsupporting a patient in a lying position in accordance with anembodiment of the present invention;

FIG. 17 schematically illustrates a support attachment which comprisestwo wing portions adapted to support a patient in a lying position fromeither side in accordance with an embodiment of the present invention;and

FIG. 18 schematically illustrates a support attachment which comprisestwo attachable and/or foldable wing portions in accordance with anembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 to 18, where like elements are designated by likereferences,-various exemplary embodiments of the radiation system andmethod of the present invention will now be described. In general, theradiation system includes a gantry comprising a radiation source forgenerating a radiation beam to irradiate a portion of a body, a detectorspaced from the radiation source, and a structure positioned between thebody and the gantry. In the present specification, the invention isdescribed with embodiments where a human breast is irradiated, forexample, for the purpose of forming an image thereof. It will beappreciated that the claimed invention may be used on animals as well ashumans, and may be used on different body parts. The structure isdescribed in the illustrative embodiments as a protective barrier thatprevents at least a portion of the radiation from reaching otherportions of the body, but can perform different or additional functions.For example, the structure can perform one or more functions such as:radiation barrier, patient support, patient positioning, patientimmobilization, and patient protection from moving parts, for example.

FIG. 1 schematically illustrates a radiation system 10 in accordancewith a specific embodiment of the present invention. Radiation system 10includes a gantry 12 capable of rotating about a horizontal axis 14.Gantry 12 includes a radiation source 16 for generating a radiation beam18 for irradiating a breast 20 of a patient 22, and a detector 24 spacedfrom radiation source 16 for detecting the radiation beam transmittedthrough breast 20. A barrier 26 is positioned between patient 22 andgantry 12.

Radiation source 16 is capable of generating radiation beams atdifferent energy levels. Radiation source 16 may include a single beamgeneration module or multiple beam generation modules (not shown). Inaccordance with a specific embodiment of the present invention,radiation source 16 is configured to generate x-ray radiation beams at akilo-electron-volt (keV) energy level and a mega-electron-volt (MeV)energy level. A keV energy level x-ray radiation beam is generally usedfor forming images of tumor and/or tissues in patient, and is thereforealso referred to as an image beam or a diagnostic beam. A MeV energylevel x-ray radiation beam is generally used for targeting and treatingtumor or other abnormal tissue in patient. The MeV energy level x-rayradiation beam can also be used for forming images of patient. However,images formed using an MeV energy level x-ray beam typically have lowercontrast and spatial resolutions than those formed with an x-ray beam ata lower energy level, e.g., keV energy level. The MeV energy levels havethe advantage that they reduce CT image artifacts, like rings and rays,generated by dense regions of patient anatomy, like bones and metalimplants. In accordance with an embodiment of the present invention,radiation source 16 includes two x-ray beam generators 16a and 16b (FIG.5), one for generating the keV energy level x-ray image beams andanother for generating the MeV energy level x-ray radiation beams. Thetwo beam generators may be located in close proximity with each other orseparated from each other. For example, in one specific embodiment, thetwo beam generators are so located that they project radiation beamstoward the breast at an angle of approximately 90 degree from eachother. In accordance with another embodiment, radiation source 16includes a signal x-ray beam generator that is capable of generatingx-ray beams at multiple energy levels. An embodiment uses dual (e.g. keVand MeV) energies to provide additional medically relevant information.For example, by use of dual energy techniques that include projectionimage subtractions or ratioing, or other simple or complex (e.g.correlation and mutual information) mathematical operations on the dualenergy data well known in the art, including such operations as afunction of time, embodiments provide increased sensitivity, to elementslike contrast agents, and evaluations of functional performanceparameters, such as perfusion and cellularity. By way of example, U.S.patent application Ser. No. 10/033,327 entitled “Radiotherapy ApparatusEquipped with an Articulable Gantry for Positioning an Imaging Unit” andfiled on Nov. 2, 2001 discloses a system with x-ray radiation sources atdifferent energy levels, the disclosure of which is incorporated hereinby reference in its entirety.

A beam adjuster 28 (FIG. 6) may be included in gantry 12 in front ofradiation source 16 to adjust the shape, size, intensity, and directionof radiation beam 18. In a specific embodiment, beam adjuster 28includes one or more multiple leaf collimators. In an alternativeembodiment, beam adjuster 28 includes one or more multiple leafcollimators and one or more single jaw collimators.

Detector 24 is capable of detecting images of tumor and surroundingtissues in patient formed by x-ray beams at both the MeV high energylevel and the keV low energy level. In accordance with an embodiment,detector 24 includes two image detecting devices 24 a and 24 b (FIG. 5),one for detecting images formed by the keV image beams, and the otherfor detecting images formed by the MeV radiation beams. In accordancewith another embodiment, detector 24 includes a single image detectingdevice that is capable of detecting images formed by beams at multipleenergy levels. By way of example, U.S. patent application Ser. No.10/013,199 entitled “X-Ray Image Acquisition Apparatus” and filed onNov. 2, 2001 discloses an x-ray image detecting device that is capableof detecting multiple energy level x-ray images and can be used asdetector in accordance with the present invention. U.S. patentapplication Ser. No. 10/013,199 is incorporated herein by reference inits entirety. In accordance with a specific embodiment of the presentinvention, detector 24 is a flat plate x-ray sensor.

System 10 can include a control module (not shown) coupled to gantry 12,radiation source 16, beam adjuster 28, and detector 24 to control theiroperations.

It should be noted that system 10 in accordance with the presentinvention is not limited to having the structure as described hereinabove. For example, radiation source 16 is not limited to generatingx-ray radiation at the keV and MeV energy levels. Depending on thenature of treatment or application, radiation source 16 may generatex-ray radiation at other energy levels or generate other kinds ofradiation beams, which include, but are not limited to, beta ray beams,positron beams, proton beams, antiproton beams, neutron beams, heavy ionbeams, e.g., alpha ray beams, carbon ion beams, etc. Detector 24 mayinclude different kinds of radiation sensors corresponding to differentradiation beam sources. Further, system 10 is not limited to having onedetector as shown in FIG. 1. In alternative embodiments, system mayinclude two or more image detectors.

Barrier 26 is positioned between patient 22 and gantry 12 to protect therest of the patient's body from radiation. Barrier 26 can also performthe functions of supporting patient 22 for correct and stable positionand protecting patient 22 from collision with moving gantry 12. Barrier26 can be mounted on the ceiling and the floor of the treatment room inwhich system 10 is installed. Barrier 26 can be in various forms andsizes depending on specific applications. By way of example, FIGS. 1-4show a barrier in the form of a shallow cone having circular symmetryfor illustration purpose. Other alternative embodiments include shallowpartial spheroids, curved shapes, or shallow pyramids formed by multipleplanar surfaces. Alternatively, barrier 26 can be formed by acombination of curved and planar surfaces. FIGS. 8-13 show alternativeembodiments of barrier 26, which will be described in more detail below.

In some embodiments, barrier 26 comprises materials that absorbradiation such as x-ray beam 18. Suitable radiation absorbing materialsare well known in the art, which include, but are not limited to: lead,tungsten, tantalum, uranium, thorium, iridium, gold, and their alloys ormixtures or in binders that contain them including glass, plastic, andsheet rock. In a specific embodiment, barrier 26 is formed of leadedsheet rock. Near the region of the patient's breast 20, barrier 26 caninclude a material that has a low absorption of radiation beam 18 toallow free penetration to areas of interest such as the chest wall ofthe patient.

Barrier 26 is provided with an opening 30 (FIGS. 3 and 4) adapted toallow a breast 20 and chest wall passing therethrough to be exposed toradiation beam 18. FIG. 2 schematically shows the detail of anuncompressed breast 20 extended through opening 30 in barrier 26. Asshown in FIG. 2, a holder 32 is coupled to barrier 26 for receiving andsupporting uncompressed breast 20. By way of example, holder 32 can be ahollow cylinder having an end cap 34. End cap 34 can be removable toallow a radiation technician to place and position breast 20 in hollowcylinder 32. A soft gasket 36 can be attached to hollow cylinder 32 toprovide vacuum seal near the chest wall boundaries of breast 20. Avacuum line 38 can be coupled to hollow cylinder 32 for evacuating thecylinder. Vacuum line 38 allows breast 20 to be more completely drawninto and stabilized in hollow cylinder 32 and into radiation beam 18.Both holder 32 and gasket 36 can be made of a material that has a lowabsorption of x-ray beam so that clear imaging of breast anatomy is notcompromised. A panic button (not shown) can be provided in barrier 26 orheld in a free hand of patient 22. When the panic button is pushed, thevacuum in hollow cylinder 32 is turned off so that patient 22 hascontrol of releasing herself from breast support cylinder 32 at anytime. A plurality of small holes 40 can be provided in the areaproximate opening 30 to prevent formation of vacuum beyond the immediateregion of breast 20.

Barrier 26 can be provided with another opening 42 (FIGS. 3 and 4)adapted to allow an arm of patient 26 passing therethrough. Acylindrical support 32 is coupled to barrier 26 for receiving andsupporting the extended arm. A hand bar 48 can be provided e.g. at oneend of cylindrical support 46 to assist patient 22 to hold and stabilizethe extended arm. Cylindrical support 46 can be made of the samematerial as that of barrier 26. Alternatively, cylindrical support 46 ismade of a different material. In some embodiments, cylindrical support46 comprises a material that absorbs radiation beam 18 such as x-raybeams. In some embodiments, near the region of patient's chest wall andbreast, cylindrical support 46 comprises a material that has lowabsorption of radiation so that radiation beam 18 passes through forclear imaging of the chest wall, the breast and its associated tissues.As will be described below, cylindrical support 46, when combined withlimited angles of gantry rotation, can effectively protect the bones andmuscles of patient's arm and shoulder from radiation.

FIGS. 3 and 4 are plane views of exemplary barriers 26 in accordancewith an embodiment of the present invention. In a specific embodimentshown in FIG. 3, barrier 26 is designed to have openings 30 and 42adapted to allow patient's left breast and left arm passingtherethrough. In another specific embodiment shown in FIG. 4, barrier 26is designed to have openings 30 and 42 adapted to allow patient's rightbreast and right arm passing therethrough.

In some embodiments, barrier 26 can be divided into a first innersection 50 and a second outer section 52 by dotted line 54 as shown inFIGS. 3 and 4. Second outer section 52 can be mounted to the ceiling andthe floor of the treatment room in which system 10 is installed. In aspecific embodiment, first inner section 50 with openings can bedetachable from second outer section 52 and replaceable. Thus, the sizeof opening 30 in first inner section 50 can be chosen to adapt tovarious size of patients' breasts. In another specific embodiment, firstinner section 50 is rotatable with respect to second outer section 52along dotted line 54. For example, first inner section 50 can be rotatedcounterclockwise to a position shown in FIG. 3 suitable for use inirradiating patient's left breast. Conversely, first inner section 50can be rotated clockwise to a position shown in FIG. 4 suitable for usein irradiating patient's right breast.

In some embodiments, a slot 56 is provided between openings 30 and 42.Slot 56 is sized and shaped such that the soft tissue leading frombreast 20 to the arm pit (axillary extension of the breast) extendstherethrough to be exposed to radiation beam 18. This allows irradiationand imaging of the soft tissue leading from an uncompressed breast tothe armpit. It is advantageous to image both the breast and its axillaryextension since primary breast lesions often spread to infect lymphnodes in this region.

In some embodiments, barrier 26 can be provided with two arm openingsadapted to sequentially allow each of the two arms passing through. Forinstance, one of the two arm openings is adapted to allow the left armpassing through when the patient's left breast is extended throughopening 30 and exposed to radiation beam 18. Another arm opening isadapted to allow the patient's right arm passing through when thepatient's right breast is extended through the same opening 30 andexposed to radiation beam 18. In these embodiments, each of thepatient's breasts can be sequentially irradiated without the need ofrotating first inner section 50 or modifying barrier 26.

Referring to FIG. 8, there is shown a barrier 26 in accordance withanother embodiment of the present invention. In general, barrier 26 inFIG. 8 comprises a structure in a-convex shape and configured to bepositioned near gantry 12, which is generally in a concave shape.Barrier 26 comprises a ledge portion 66, a main portion 68, and a bandportion 70 connecting the ledge and main portions 66 and 68. An L-shapedregion 72 is formed between ledge and band portions 66 and 70 and isconfigured to surround the outer perimeter of gantry 12. Main portion 68is configured to be positioned in the gantry housing and adapted tosupport patient's body 22. Openings are provided in main portion 68 fora breast passing therethrough for irradiation. A stool 58 can be coupledto band portion 70 on which patient 22 can sit during imaging. In someembodiments, ledge 66, band 72 and main 68 portions are coupled togetherby conventional means such as by using bolts and nuts or by welding,etc. In some embodiments, the ledge, band and main portions are anintegral unit. In one embodiment, stool 58 is an integral portion ofbarrier 26.

When barrier 26 is positioned near gantry 12, for example, being mountedto the ceiling and floor of the treatment room, free space can becreated between the L-shape region and the ceiling and floor. Gantry 12can freely rotate in the free space without collision with barrier 26and patient's body 22. One of the advantages of barrier 26 in FIG. 8 isthat the patient can be positioned further inside rotating gantry 12 sothat irradiation beam 18 can be projected onto the breast and/or itsaxillary extension and/or its chest wall without the need to modify moststandard gantries, which typically have radiation sources located in thecentral region of the source enclosure. Thus, the use of barrier 26 caneliminate the need to move radiation source 16 to the perimeter edge ofgantry 12.

Referring to FIG. 9, there is shown a breast support 74 in accordancewith another embodiment of the present invention. In comparison with thebreast holder 32 shown in FIG. 2 which comprises a sealed hollowcylinder having an evacuating means, support 74 in FIG. 9 comprises anopen ledge that supports the breast 20 from underneath. Support 74 cancomprise a flat plate oriented horizontally or at some small angle (e.g.5 to 30 degrees) to a horizontal axis. In some embodiments, support 74can comprise a curved surface to conform to the form of an uncompressedbreast. In some embodiments, support 74 comprises a combination of flatand curved surfaces. In some embodiments, support 74 comprises aflexible material that provides positioning and immobilization for thebreast, such as like a bra.

In operation, in one embodiment, patient 22 sits on a stool 58, oralternatively, stands in front of barrier 26 in a substantially uprightposition. Alternatively stool 58 can be incorporated in barrier 26.Patient 22 rests against and is supported by barrier 26 and extends abreast 20 (e.g., the left breast as in FIG. 1) through an opening 30 inbarrier 26 to be exposed to radiation beam 18. A radiation technicianmay assist in placing and positioning the breast 20 in holder 32 orsupport ledge 74. A vacuum pump (not shown) is turned on to providevacuum so that the breast 20 is more completely drawn into andstabilized in holder 32. Patient 22 can also extend an arm (e.g., theleft arm) through an opening 42 and grasp a hand bar 48 to rest the armin support cylinder 46. Soft tissue leading from breast 20 to axillaextends through slot 56 to be exposed to radiation beam 18. Anuncompressed breast 20 and soft tissue leading from the breast to axillaare thus ready for irradiation and imaging. Contrast agents can beoptionally injected into uncompressed breast 20 to facilitate assessingsuspicious lesions.

Radiation source 16 generates radiation beam 18 such as a cone x-raybeam. The cone x-ray beam can be at any x-ray energy level fromkilovoltages (KeV) to megavoltages (MeV). For example, the cone x-raybeam generated by radiation source 16 can be at an energy level in therange from about 50 kVp to about 30 Mv. In one embodiment, the conex-ray beam can be at an energy level in the range from about 200 kVp toabout 1000 kVp. In an embodiment shown in FIG. 5, radiation source 16includes two x-ray beam generators: a kilovoltage x-ray beam generator16 a and a megavoltage x-ray beam generator 16 b. Each of the two x-raybeam generators 16 a and 16 b is provided with a flat plate sensor 24 aand 24 b. In one embodiment, the pair of kilovoltage x-ray beamgenerator 16 a and flat panel sensor 24 a are mounted at 90 degrees tothe pair of megavoltage x-ray beam generator 16 b and flat plate sensor24 b in gantry 12. This configuration produces both a kilovoltage x-raybeam and a megavoltage x-ray beam. In one embodiment, generator 16 agenerates a cone x-ray beam at an energy level of approximately 125 kVpfor diagnostic imaging of a breast and its axillary extension and chestwall. In another embodiment, generator 16 b generates a cone x-ray beamat an energy level of approximately 1-2 MV for radiotherapy and fordiagnostic imaging with reduced ray and ring artifacts. As gantry 12rotates around an axis such as a horizontal axis 14, projection and CTimages, for diagnosis, staging, treatment planning, treatment targeting,and motion management, can be generated at kilovoltage and/ormegavoltage energies and be immediately followed by radiation therapy atmegavoltage energies.

Radiation beam 18 generated by radiation source 16 impinges on a densex-ray absorbing block 28 shown in FIG. 6 to provide an x-ray beam with aspecific shape, size, intensity, and direction of x-ray beam 18. In aspecific embodiment shown in FIG. 6, a multileaf collimator 28 isdisposed in front of radiation source 16 to produce a half cone x-raybeam with a sharp vertical edge 60 and semi-circular cross-section 62.Half cone beam with sharp vertical edge 60 is advantageous in reducingradiation dose to tissues of healthy body parts near the breast 20. Themultileaf collimator 28 can be adjusted to other advantageous shapes,other than a flat boundary, such as a curved or bumpy surface of thelungs, so that the latter is better protected from the x-ray beam.

Gantry 12 rotates about an axis 14 such as a horizontal axis ascontrolled by a control module (not shown). As gantry 12 rotates,radiation beam 18 generated by radiation source 16 is projected ontobreast 20 and its axillary extension from different directions. By wayof example, cone x-ray beam is generated from radiation source 16 andprojected onto breast 20 and soft tissue. Gantry 12 rotates 360 degreesor alternatively slightly more than 360 degrees (e.g. approximately 370degrees) and approximately 500 to 600 projection images are taken atequally spaced angles to provide a complete set of projection data.Gantry 12 can also tilt from its horizontal position and rotates aboutan axis having an angle with horizontal axis 14 from about 0 to 85degrees so that radiation beam 18 is projected to breast 20 from variousangles. In some embodiments, gantry 12 rotates 180 degree plus the conebeam angle in a way that radiation beam 18 does not first pass throughpatient's shoulder and arm region prior to entering the breast area, toreduce radiation dose to healthy arm and shoulder tissue and bonevolume. The portion of cylindrical support 46, through which no directradiation beams pass on the way to the breast 20 and detector 24, can bemade of a radiation absorbing material to protect patient 22 fromscatter radiation exposure.

Detector 24 detects the radiation beam transmitted through breast 20 andproduces radiation transmission data representing the intensity of theradiation transmitted through breast 20. An image processor (not shown)receives the transmission data from detector 24 and produces a pluralityof single projection images, typically 500 to 600, that are thenreconstructed into three-dimensional CT image data sets of breast 20,using reconstruction algorithms known in the art such as the Feldkampalgorithm.

After one breast (e.g., the left breast) is irradiated, the other breast(e.g., the right breast) can be exposed to radiation beam for imaging.This can be done by detaching first inner section 50 of radiation 26 andreplacing with another inner section having openings designed for theright breast. Alternatively, inner section 50 is rotated clockwise to aposition suitable for the right breast and right arm extending throughthe openings. In some embodiments, patient 22 can reposition herself toextend her right breast and right arm through the openings in barrier26.

In another aspect of the invention for radiation therapy, both akilovoltage x-ray source 16 a and detector 24 a and a megavoltage x-raysource 16 b and detector 24 b can be mounted onto a rotating gantry 12and oriented at 90 degrees to each other as shown in FIG. 5. In someembodiments, the orientation of the axis of rotation 14 is horizontalwhere FIG. 5 is a front view and the patient's 22 head-tofoot-orientation is substantially vertical. In some embodiments, patient22 lies in a prone or supine position and gantry 12 rotates about avertical rotation axis 14 under patient 22. In such embodiments, FIG. 5is a top view and the patient's 22 head-to-foot orientation issubstantially horizontal. In some embodiments, patient 22 lies in asupine position and gantry 12 can be suspended above patient 22 androtates about a vertical axis of rotation 14. In such embodiments, FIG.5 is a bottom view and the patient's 22 head-to-foot orientation issubstantially horizontal. In some embodiments, the patient'shead-to-foot orientation can be in any plane from vertical tohorizontal, or stated alternatively, the angle between patient'shead-to-foot orientation and a vertical axis can be at any desiredangle.

Gantry 12 is rotated with the kilovoltage source 16 a on to acquire acomplete kilovoltage cone beam CT data set. This can be a complete 360rotation. In some embodiments, gantry 12 rotates 180 degrees plus thecone beam angle (e.g., 20 to 30 degrees) so that the kilovoltage x-raysdo not pass first through the shoulder and arm of patient 22.

In another aspect of this invention, the arm support structure(including a cylindrical tube and/or curved tube-like structure or acombination of the two) contains radiation absorbing material ormaterials to reduce the radiation dose to healthy tissues of theinserted shoulder and arm or to parts of them.

The kilovoltage x-ray source 16 a can be configured to have its beamemerge from the boundary edge of gantry 12 near patient 22 as shown inFIG. 1. The kilovoltage source beam 18a can be shaped with an x-rayabsorbing block 28 as shown in FIG. 6, to provide a half cone shape 62as shown in FIG. 7. This allows the incident kilovoltage beam 18 a topass through the muscle of the patient's 22 chest wall with minimalexposure to the head and neck, the heart and lungs, and the otherhealthy parts of the patient's body 22.

Barrier 26 can be configured to block kilovoltage x-ray beam 18 a or itsscattered components that do not travel directly from source 16 a tokilovoltage detector 24 a and pass through the breast 20 or its axillaryextension toward the arm pit. Barrier 26 can also be configured totransmit kilovoltage X-rays 18 a that pass through the muscle of thechest wall adjacent to the breast 20. As described above, the breast 20is placed into hollow cylinder 32 for stable positioning and support. Anend cap 34 and vacuum line 38 can be attached to hollow cylinder 32 toassist in obtaining proper placement of the breast 20 relative to thekilovoltage x-ray beam source 16 a and detector 24 a.

The megavoltage x-ray beam source 16 b can be more centrally locatedfrom the boundary of gantry 12. In some embodiments, beam source 16 bcan be positioned by gantry 12 to several (e.g., 2 to 8) angles andorientations to deliver a proscribed megavoltage dose to the breast 20,its axillary extension toward the arm pit, and the muscle wall of thechest adjacent to the breast 20 and avoid a large dose delivery to othersensitive areas, such as the head, neck, heart and lungs of the patient22. Selection of such specific megavoltage orientations and angles iswell known to radiation oncology practitioners and has been described byS. V. Formenti et al. in International Journal of Radiation Oncology,Biology, and Physics, Vol. 60, 2004, pp. 493-504.

The location, extent, shape, orientation and/or boundaries of themalignant tumor are precisely determined in three dimensional space,relative to the gantry 12 system coordinate, by the kilovoltage source16 a and detector's 24 a acquisition of a cone beam CT data set. Thesedata are analyzed to either compare these specifications to apreexisting treatment plan or to produce a new or a modified treatmentplan. Then a desired dose, to the whole breast 20 and/or its axillaryextension and/or its adjacent chest wall muscle, or to a restrictedvolume containing the malignant tumor, is accurately delivered bymegavoltage source 16 b, monitored by detector 24 b such as a flat panelmegavoltage sensor, all on the single gantry 12 and all during a shorttime span (e.g., less than 30 minutes) for a single dose delivery. Sincemegavoltage x-ray beam radiotherapy is routinely administered in manyseparate daily doses, called fractions, over many weeks, this type ofmonitoring allows some determination of the tumor's response totreatment. This response can be indicated by comparisons to earlierfractions, as evident by changes in location, extent, shape,orientation, boundaries, or by detection of contrast agents related tofunctional, biological and/or structural characteristics, where theseagents are administered as a part of the treatment setup and delivery,and the evaluation is from cone beam CT data set viewing and analysisprocedures. The time response of contrast agent uptake and flush outcontributes medically relevant information on the properties andcharacteristics of the cancer lesions and their surrounding tissues. Thethree dimensional CT data sets can be extended to the 4^(th) dimensionof time by using respiratory gating during the cone beam CT acquisitionto correlate position with the phase of the patient's 22 breathingprocess.

FIGS. 10-11 illustrate another embodiment of barrier 26, which isadjustable to adapt to various positions of patient's body 22. In thisembodiment, the material forming barrier 26 is selected such thatbarrier 26 is bendable arid/or adjustable to adapt to a desired positionof patient 22 when in use. The adjustable barrier 26 is sufficientlyrobust to support patient's body 22 leaning against the barrier.Suitable materials for forming adjustable barrier 26 include but are notlimited to aluminum.

In some embodiments, adjustable barrier 26 is in the form of a skeletalframe that includes a minimum number of components needed to support orposition patient 22 in a desired position. In general, a skeletal framecomprises a minimalist structure that provides support and/orpositioning of the patient and/or other structures such as positioningdevices and radiation barriers. Suitable materials for constructing askeletal frame include aluminum, stainless steel, chrome molly steel,fiberglass, plastics, and carbon fiber materials and composites. Askeletal frame may optionally incorporate some positioning and shieldingif desired. Lead lined curtain and/or cushion pad may be attached to theskeletal frame. As one example, when barrier 26 in form of a skeletonframe is in use, patient 22 may wear a lead lined uniform such as a leadlined hospital gown that opens in the back or a lead lined gown shirtand apron to protect other healthy body parts from unnecessaryirradiation. A separate, flexible lead lined sleeve can be placed aroundpatient's hand, and part of the arm to provide further protection. Ifdesired, a shin guard plate can be attached to the frame near floor 84of the treatment room to protect any body parts exposed below the bottomof the gown or apron. One of advantages of barrier 26 shown in FIGS.10-11 is that it can be made compact and easily installed by, forexample, bolts and nuts in the treatment room and conveniently removed.Alternatively, the system may be made such that it may be positionedrelative to an imaging or treatment system without attachment, by forexample, having some type of mating registration points that fitsecurely onto a portion of the imaging or treatment system. For example,barrier 26 can be installed between a gantry 12 and a couch 86 of anexisting cone beam CT system without any major modification of thesystem. After patient's breasts are imaged and/or treated, barrier 26 isremoved so that the CT system can perform imaging and/or treatment ofother body parts of a patient. For instance, a patient can now lie on acouch top 88, which can be moved into gantry 12 after the barrier 26 isremoved.

FIGS. 12-16 illustrate further embodiments of the present invention inwhich patient 22 can sit or lie side ways on couch top 88 during imagingand/or treatment. Barrier 26 is coupled to an end or other location ofcouch top 88 and configured to support and protect patient 22. While notshown in FIGS. 12-16, couch 86 may include a moveable portion (notshown) driven by a moving mechanism such as precision motors. Themoveable potion can be translated in three directions (x, y, and z).Couch 86 may be provided with a titling mechanism for titling themoveable portion with respect to the x-y plane. Couch top 88 is coupledto the moveable portion and can be translated and/or titled with thecouch's moveable portion. Couch top 88 can also be moved independent ofthe moveable portion. For example, couch top 88 can be independentlytranslated in x-direction to move patient 22 into and out of gantry 12.

A support attachment 90 can be coupled to and moved with couch top 88.By way of example, support attachment 90 can be an aluminum framesecured to couch top 88. Support attachment 90 can be secured to couchtop 88 by various means known in the art. For example, supportattachment 90 can be hooked to couch top 88 at one end so that it can beconveniently removed after imaging and/or treatment of patient's breast.Support attachment 90 can be moved together with couch top 88. Forexample, support attachment 90 can be translated in three dimensions andtilted. In some embodiments, support attachment 90 can be movedindependent of couch top 88. As shown in FIGS. 15-16, support attachment90 can be rotated in the plane of couch top 88.

While support attachment 90 is illustrated and described withembodiments of an existing imaging system including a moveable couchtop, it will be appreciated that support attachment 90 can be used indesigning a mammography CT system. In such a mammography CT system,support attachment 90 may be coupled to a couch base, which can beprovided with a moving mechanism capable of translating, tilting, and/orrotating support attachment 90.

Barrier 26 such as an adjustable support illustrated in FIGS. 10-11 canbe coupled to support attachment 90 at one end by various means known inthe art. Barrier 26 can be in the form of a skeleton frame consisting ofa minimum number of parts needed to support patient 22. A skeletal frame26 may optionally incorporate some positioning and shielding if desired.As one example, a leaded curtain can be placed on the skeleton frame toblock any unnecessary radiation of patient's healthy body parts. A thinmetal sheet such as aluminum sheet can also be used. Alternatively,patient 22 may wear a leaded uniform such as a lead lined hospital gownthat opens in the back or a lead lined gown shirt and apron to protectother healthy body parts. Openings are provided in the leaded curtainand/or metal sheet to allow patient's breast and its axillary extensionpassing through.

FIG. 13 illustrates an embodiment of the present invention in which aportion such as one end of support attachment 90 is configured to adaptto patient's body build. As shown, support attachment 90 may include adrop-down portion 92 at one end to adapt to tall patients. Drop-downportion 92 is desirable for tall patients in aligning their breastsand/or axillary extension with the gantry's rotation axis 14.Alternatively, support attachment 90 may include a raise-up portion (notshown) to adapt to short patients in aligning their breasts withgantry's rotation axis 14.

FIGS. 15-16 illustrate an embodiment of the present invention in whichpatient 22 may lie on her side on a support attachment 90 during imagingand/or treatment. As shown, support attachment 90 is coupled to couchtop 88 at an angle that allows patient 22 to lie on her side withoutmajor body contortion. Barrier 26 is coupled to support attachment 90and provided with an opening 96 that allows breast 20, its axillaryextension, and optionally an arm passing through. Breast 20 is supportedon support ledge 74 and exposed to a radiation beam. Support 91 isprovided to secure and support barrier 26. This embodiment greatlyreduces body contortion and provides greater comfort for patients 22. Inan embodiment, support attachment 90 can be rotated in the plane ofcouch top 88, independent of the movement of couch top 88. In anotherembodiment, barrier 26 is an integral portion of support attachment 90and moveable during patient positioning.

FIG. 17 illustrates another embodiment of support attachment 90, whichis adapted to allow patient 22 to lie down from either side so that bothbreasts and their associated tissues can be easily imaged. As shown,support attachment 90 can be in Y- or V-shape having two wing portions90 a and 90 b and a central portion 90 c. Two wing portions 90 a and 90b may be angled such that patient 22 can lie down comfortably on herside on either wing portion without major body contortion. Barrier 26(not shown in FIG. 17) can be coupled to central portion 90 c.

FIG. 18 illustrates another embodiment of support attachment 90, whichcomprises two attachable and/or foldable wing portions 90 a and 90 b.Various mechanisms known in the art such as slides and brackets can beused to attach and/or fold wing portions 90 a and 90 b. In oneembodiment, wing portions 90 a and 90 b are attachable to couch top 88and foldable against couch 86. In such embodiment, wing portions 90 aand 90 b are moveable with couch top 88. In another embodiment, wingportions 90 a and 90 b can be coupled to a gantry housing 92 such as ofa ring gantry CT system. There exists a need for very fast cone beam CTof breasts. For instance, when X-ray contrast agents are injected intothe blood stream, it is desirable that the transport of the contrastagents with time is imaged so that more precise information can beobtained on the target lesion or lesions and their response totreatments, like external beam radiotherapy. In an enclosed gantry CT,the rotation speed can be on the order of 0.3 to 0.4 seconds perrotation. At such high rotation speeds, an enclosed gantry is desiredfor safety. FIG. 18 schematically shows an enclosed ring gantry CTsystem having a cylindrical tunnel opening 94. When wing portions 90 aand 90 b are attached to gantry housing 92, couch top 88 can freely movein and out opening 94, independent of the side wing portions 90 a and 90b attached to gentry housing 92.

In use, patient 22 sits on e.g. one end of support attachment 90 andleans against support frame 26 as shown in FIGS. 12-13. Alternatively,patient 22 may lie on her side on support attachment 90 as illustratedin FIGS. 15-18. Patient 22 is positioned such that a breast and/or itsaxillary extension extend through the opening(s) provided in barrier 26and are supported in breast support 32 or 74. The couch's moveableportion and/or couch top move patient 22 into gantry 12 at a positionthat exposes the patient's breast and/or its axillary extension toradiation beam 18. The elevation (z-direction) of the couch's moveableportion is adjusted such that the patient's breast and/or its axillaryextension substantially align with the axis of rotation 14 of gantry 12.Couch top 88 can also be adjusted by the tilting mechanism provided incouch 86. Support attachment 90 may also be rotated during theadjustment.

The above various embodiments of the present invention are described inthe context where one breast is imaged and/or treated at one time. Itshould be pointed out that if both breasts need to be imaged and/ortreated, both breasts 20 a and 20 b and their axillary extension can besimultaneously irradiated, as illustrated in FIG. 14. This can beachieved by providing, for example, two openings in barrier 26 to allowboth breasts and/or their axillary extension passing through. Oneadvantage of irradiating both breasts simultaneously is that it can notonly save time but also reduce radiation doses to patients.

The present invention provides a system and method for providingthree-dimensional computed tomography and radiotherapy of tumoroustissues in patient's uncompressed breasts. This eliminates the painsuffered by patients in conventional mammography during which thebreasts are compressed. Contrast agents circulate more effectively inuncompressed breasts and can be advantageously used in the presentinvention to facilitate assessing suspicious lesions. Another advantageof the present invention is that not only the breasts themselves, butalso the soft tissues leading from the breasts to the axilla (arm pit)and the muscle of the chest wall, can be irradiated and examined, whilethe radiation dose to healthy heart, lung, and other body part tissuesis minimized. Moreover, the present system and method can make immediateuse of widely available CT gantry systems and external beam radiotherapysystems, which primarily have axes of rotation that are horizontal. Theclear position, shape and volume information on any malignant lesionsfrom the breast through the axilla can be coupled to a system forefficient and prompt radiotherapy via external beam radiotherapy and/orbrachytherapy.

The foregoing description of specific embodiments and examples of theinvention have been presented for the purpose of illustration anddescription, and although the invention has been described andillustrated by certain of the preceding examples, it is not to beconstrued as being limited thereby. They are not intended to beexhaustive or to limit the invention to the precise forms disclosed, andmany modifications, improvements and variations within the scope of theinvention are possible in light of the above teaching. It is intendedthat the scope of the invention encompass the generic area as hereindisclosed, and by the claims appended hereto and their equivalents.

1. A structure for use in irradiating a portion of a body in a gantrywhich is rotatable about a horizontal axis and comprises a radiationsource for generating a radiation beam and a detector spaced from theradiation source, said structure being adapted to be positioned betweenthe body and at least a portion of the radiation beam and being providedwith an opening adapted to allow a portion of the body passingtherethrough to be exposed to the radiation beam.
 2. The structure ofclaim 1 wherein the portion of the body is a breast of a patient.
 3. Thestructure of claim 1, which comprises an first area proximate theopening and encompassing an additional portion of the body proximate theportion of the body, and a second area, said first area transmittingradiation to a greater extent than said second area.
 4. The structure ofclaim 2, which is provided with an opening adapted to allow the breastand tissue leading from the breast to arm pit passing therethrough to beexposed to the radiation beam.
 5. The structure of claim 1, whichfurther comprises a holder for supporting the portion of the body. 6.The structure of claim 5 wherein the holder is substantially cylindricaland comprises an end cap that is removable for facilitating positioningof a breast in the holder.
 7. The structure of claim 6, which furthercomprises means for evacuating the holder.
 8. The structure of claim 7,which further comprises a gasket for sealing the breast in the holder.9. The structure of claim 7, which further comprises a panic buttoncoupled to the evacuating means.
 10. The structure of claim 1, which isfurther provided with a plurality of holes surrounding the opening forpreventing formation of vacuum in a region beyond the portion of thebody.
 11. The structure of claim 2, which is further provided with anadditional opening adapted to allow an arm of the patient passingtherethrough.
 12. The structure of claim 2, which is in the shape of acone, partial spheroid, or pyramid.
 13. The structure of claim 12wherein the structure comprises an inner section and an outer section,said inner section is detachable from the outer section and providedwith the opening.
 14. The structure of claim 13 wherein the innersection is rotatable with respect to the outer section such that thelocation of the opening in the barrier is changeable.
 15. The structureof claim 5, wherein the holder comprises a surface conformal to aportion of an uncompressed breast and supporting the breast fromunderneath.
 16. The structure of claim 1, wherein a portion of thestructure including the opening protrudes inward the gantry such thatthe portion of the body is positioned for irradiation by the radiationsource disposed a distance from an edge of the gantry.
 17. The structureof claim 1, which is adjustable to adapt to a desired position of thepatient.
 18. The structure of claim 17, which is in the form of askeleton frame.
 19. A structure for use in irradiating a breast of apatient in a gantry which comprises a radiation source for generating aradiation beam and a detector spaced from the radiation source, saidstructure being adapted to be positioned between the patient and thegantry and being provided with a first opening adapted to allow a breastpassing therethrough to be exposed to the radiation beam and a secondopening adapted to allow an arm passing therethrough.
 20. The structureof claim 19, which comprises an first area proximate the opening andencompassing an additional portion of the body proximate the portion ofthe body, and a second area, said first area transmitting radiation to agreater extent than said second area.
 21. The structure of claim 19,which is further provided with a slot between the first and secondopenings adapted to allow tissue leading from the breast to axillapassing therethrough to be exposed to the radiation beam.
 22. A methodof irradiating a portion of a body, comprising the steps of: providing agantry, said gantry comprising a radiation source for generating aradiation beam and a detector spaced from the radiation source;providing a structure near the body; said structure provided with anopening adapted to allow a portion of the body passing therethrough;extending a portion of the body through the opening in the structure toexpose the portion to the radiation beam; rotating the gantry about ahorizontal axis, whereby the portion of the body is irradiated by theradiation beam and detected by the detector.
 23. The method of claim 22wherein the portion of the body is a breast of a patient.
 24. The methodof claim 22 wherein the portion of the body is a breast of a patient andtissue leading from the breast to arm pit.
 25. The method of claim 23,which further comprises the step of extending an arm of the patientthrough an opening in the structure.
 26. The method of claim 22, whereinthe step of rotating comprises rotating the gantry in 180 degrees plus acone beam angle such that a majority of projections of the radiationbeam do not traverse the patient's head and/or neck and/or arm prior totraversing the breast.
 27. A system for irradiating a breast of apatient, comprising: a gantry comprising a radiation source forgenerating a radiation beam and a detector spaced from the radiationsource; and a structure positioned near the patient, said structure isprovided with a first opening adapted to allow a breast passingtherethrough to be exposed to the radiation beam and a second openingadapted to allow an arm passing therethrough.
 28. The system of claim 27wherein the gantry is rotatable about a horizontal axis.
 29. The systemof claim 27 wherein the structure is further provided with a slotbetween the first and second openings adapted to allow tissue leadingfrom the breast to arm pit passing therethrough to be exposed to theradiation beam.
 30. The system of claim 27, wherein the structurecomprises a first area proximate the opening and encompassing anadditional portion of the body proximate the portion of the body, and asecond area, said first area transmitting radiation to a greater extentthan said second area.
 31. The system of claim 27 wherein a portion ofthe structure including the opening protrudes inward the gantry suchthat the body is inward an outer reach of the gantry, and wherein theradiation source is disposed a distance from an edge of the gantry. 32.The system of claim 27, which further comprises a holder comprising asurface conformal to a portion of an uncompressed breast and supportingthe breast from underneath.
 33. The system of claim 27, which comprisesa first radiation source for generating a first radiation beam in akilovoltage energy level and a second radiation source for generating asecond radiation beam in a megavoltage energy level.
 34. The system ofclaim 33 wherein said first and second radiation sources are attached toa common gantry.
 35. The system of claim 33, wherein said firstradiation source is attached to a first gantry, and said secondradiation source is attached to a second gantry.
 36. A method forradiotherapy of a portion of a body in a gantry which comprises amegavoltage x-ray source, said method comprising the steps of: providinga structure near the body, said structure adapted to allow a body partpassing therethrough; and delivering a megavoltage radiation dose to thebody part using the megavoltage x-ray source.
 37. The method of claim 36further comprising a kilovoltage x-ray source, wherein the kilovoltagex-ray source is placed near a boundary of the gantry proximate to thebody.
 38. The method of claim 37 wherein the body part comprises a humanbreast and/or axillary extension of the breast and/or a chest wall nearthe breast, and which further comprises the step of detecting amalignant tissue in the body part prior to the step of delivering themegavoltage dose.
 39. The method of claim 38 wherein the step ofdetecting comprising determining a location and/or an extent and/or ashape and/or orientation and/or a boundary specification of themalignant tissue.
 40. The method of claim 39, which further comprisesthe step of modifying a preexisting treatment plan or producing a newtreatment plan based on the determining step.
 41. The method of claim 38wherein said megavoltage dose is delivered less than 30 minutes afterthe detecting step.
 42. The method of claim 38 further comprising thestep of detecting the malignant tissue after the step of delivering themegavoltage dose to determine a response to the megavoltage radiationdose.
 43. The method of claim 36 further comprising the step ofadministering a contrast agent to facilitate determining a response to amegavoltage radiation dose.
 44. The method of claim 36 furthercomprising the step of blocking a radiation from the megavoltage x-raysource from reaching regions beyond the body part.
 45. The method ofclaim 36 further comprising the step of extending an arm of a patientthrough the structure.
 46. A system for irradiating a breast of apatient, comprising: a gantry comprising a radiation source forgenerating a radiation beam and a detector spaced from the radiationsource; a couch spaced from said gantry; a couch top coupled to saidcouch, said couch top being moveable relative to said gantry; and astructure coupled to said couch top, said structure being positionednear the patient and provided with an opening adapted to allow a breastpassing therethrough to be exposed to the radiation beam.
 47. The systemof claim 46, which further comprises a support attachment coupled tosaid couch top, wherein said structure is coupled to said supportattachment.
 48. The system of claim 47 wherein said support attachmentcomprises a drop-down portion extended beyond said couch top.
 49. Thesystem of claim 47 wherein said support attachment is moveable in threedirections (x, y, and z).
 50. The system of claim 47 wherein saidsupport attachment is moveable independent of the couch top.
 51. Thesystem of claim 47 wherein said support attachment comprises two wingportions, each being adapted to support the patient in a lying position.52. The system of claim 51 wherein each of the two wing portions isattachable and/or foldable.
 53. The system of claim 51 wherein the wingportions are coupled to a gantry housing.